This invention relates to medicaments and, more particularly, to the therapeutical use of a phosphoprotein existing in nature which is called "Phosvitin". Since 1885 Bunge (Z. Physiol. Chem. 9,49:1885) isolated from egg yolk an iron-containing phosphoprotein complex. A few years after, Huguenenq and Morel (Compt. Rend. 140, 1065; 1905) expressed the hypothesis that such complex -- which was named by them "haemotogen"--would be involved in the formation of the fowl embryo haemoglobin. This substance awakened the interest of many scientists; however, only in 1949 Mecham and Olcott (J. Am. Chem. Soc. 71, 3670; 1949) were able to isolate from egg yolk a homogenous phosphoprotein fraction that was named by them "Phosvitin". The identity of the former "haemotogen" with such "iron-phosvitin"complex was demonstrated in 1964 by O. Greengard et al. (Biochim. Biophys. Acta 90, 406, 1964).
The presence of phosvitin having been shown in the hen's egg, an obvious consequence was that it was sought for in the eggs of other animals; in fact, Wallace et al. (Canad. J. Biochem. 44, 1647; 1966) isolated it from the eggs of vertebrata (tortoise, frog and so on); G. Schmidt et al. (Biochem. Biophys Research Communications 18, 60, 1965) from the eggs of salmon; and Y. Macco et al. (J. Biol. Chem. 241, 3822; 1966) from the eggs of certain species of fish.
Further and deeper investigation was devoted to seek for phosvitin in the blood of hen and other animals, since it was logical to suppose that its synthesis would occur in some organ and that phosvitin would be transferred from such organ to the egg yolk through the blood flow. Thus, Mock et al. (Canad. J. Biochem. Physiol. 39,109; 1961) extracted phosvitin from the blood of non-laying hens to which estrogens had been administered, whereas Heald et al. (Biochem. J. 87, 571; 1963) demonstrated that a substance identical to the phosvitin existing in the egg yolk can be found in the blood of laying hens, even if the latter have not been treated with estrogens. Further studies showed that phosvitin is synthesized in the liver and that its formation is hormone-controlled, since it is stimulated by the presence of estrogens.
From the chemical point of view, phosvitin is a phosphoprotein, that is, a protein containing removable phosphate groups which can be easily removed by treatment with alkali and enzymes (phosphokinase).
In its molecule, 17 amino acids have been identified, 50% of which is serine; hexoses (about 2.5%) and glucosamine (1.4%) are also present. The estimated molecular weight is about 40,000 to 50,000 (Allerton et al., J. Biol. Chem. 240,3892; 1965).
In the lyophilized state, phosvitin appears as an off-white odorless powder which is soluble in water, 0.9% saline and 10% MgSO.sub.4 solution, whereas it is insoluble in a solution containing less than 2.5% MgSO.sub.4 and in the usual organic solvents. Isoelectric point = pH 1.8.
Phosvitin contains 9.6 .+-. 0.3% phosphorus, 11.6 .+-. 0.4% nitrogen and 0.3 to 0.4% iron. Molar ratio P/N=2.5 to 2.9; ashes = 31 .+-. 2%.
A solution containing 0.16% phosvitin in 0.1 M potassium chloride at pH 6.5 to 6.7 has no significant absorption peak between .lambda. = 250 and .lambda. =290 millimicrons. Paper electrophoresis (Whatman 3 MM strips; 3.times.27 cm; 200 v-10 mA) of 0.3% phosvitin in borate buffer shows a spot only using the reagent specific to phosphate esters (blue spot), whereas Schwarz starch, that is a reagent specific to proteins, does not show any further spots. A further characteristic feature is that when treated with 1% toluidine blue in 7% acetic acid the paper strip shows a blue coloured spot which does not disappear when dipped in 7% acetic acid methanol solution.
By the usual procedure of polyacrylamide gel electrophoresis, phosvitin gives one or more blue bands (which are due to the formation of molecular aggregations) when treated with 1% toluidine blue in 7% acetic acid.
By column chromatography on DEAE-cellulose, phosvitin is eluted as a single homogenous fraction.
From the above it clearly appears that phosvitin is a known substance which has been extensively studied by a number of investigators. However, no pharmacological-therapeutical actions of this substance have been disclosed.